Despite increasing stroke incidence and prevalence, conventional affected arm rehabilitation offers negligible efficacy. Newer approaches emphasize repetitive, task-specific practice (RTP) with the affected arm. While these approaches are promising, they often require particular equipment to administer, can be intensive and/or taxing for the patient and therapist, and/or can be invasive. Strategies inherent in many of the above approaches are also not reimbursed by insurance plans. Thus, there remains a need for easily implemented, inexpensive, non-invasive RTP approaches for hemiparesis. Mental practice (MP) is a complementary/alternative medicine (CAM) mind-body technique in which physical skills can be rehearsed in an inexpensive, repetitive manner. This lab was the first to show that addition of MP to RTP yields significantly larger affected arm motor outcomes than conventional motor therapy in stroke. The PI's subsequent research confirmed that MP improves affected arm kinematics, and increases affected arm use and function, with this work culminating in a positive MP trial. The PI's recent work has also determined optimal MP duration at which the largest motor changes are exhibited. The next logical step is to determine MP efficacy in a Phase IIb, multicenter trial. This two-center study will randomize [100] chronic stroke patients to either: (a) MP sessions combined with RTP training;or (b) RTP training only. This will address the objective of this application, which is to determine the impact of a RTP regimen including MP in chronic stroke. Outcomes include functional limitation (primary endpoint), impairment, activity restriction in the lab and community, quality of life, and fMRI. The central hypothesis is that participation in MP + RTP will reduce functional limitation. We will test our central hypothesis and accomplish our objective by pursuing the following specific aims: (1) Determine efficacy of MP + RTP as compared to RTP on affected arm functional limitation;(2) Determine the impact of MP + RTP on affected arm outcomes;(3) Determin MP + RTP effects on cortical organization using fMRI. PUBLIC HEALTH RELEVANCE Stroke is the leading cause of disability in the United States, producing motor impairments that compromise performance of valued activities. Hemiparesis is particularly disabling, is the primary impairment underlying stroke-related disability, and the most frequent impairment treated by therapists in the United States. This study will test efficacy of a promising technique in reducing disability and increasing function, thereby improving outcomes and health, and reducing care costs, for community dwelling patients with stroke-induced hemiparesis.